SB PROP @ ARL $ARLP008
ARLP008 The ARRL Solar Report

ZCZC AP08
QST de W1AW
Propagation Forecast Bulletin 8 ARLP008

From ARRL Headquarters

Newington CT February 20, 2026
To all radio amateurs

SB PROP ARL ARLP008
ARLP008 The ARRL Solar Report

Solar activity returned to low levels this past week. The strongest event of the period was a C1.8 flare on February 17 from region 4374. This region was also responsible for a C1.4 flare on February 18. The only other flare of
note was a C1.1 flare on February 17

from an unnumbered plage region near S05E85. (A plage region is a bright, intensely hot region in the Sun's chromosphere, typically found in active
areas surrounding sunspots.)


Region 4374 exhibited minor decay through the dissipation of its trailing spots. Regions 4375 and 4377 were largely unchanged in area and complexity.


A large filament eruption beyond the southwest limb was seen in SDO and SUVI imagery starting approximately February 18. It was associated with a Type II radio sweep that began on February 18 with an estimated shock velocity of 310 km/s. The eruption was first visible in coronagraph imagery on February 18,
but initial analysis indicates no Earth-directed component. Solar activity is forecast to be at low levels, with a slight chance for M-class (R1-R2/minor-moderate) flares through February 20.


Solar wind parameters continued to reflect the waning influence of a positive polarity Coronal Hole High-Speed Stream (CH HSS). Solar wind speed followed a general declining trend, decreasing from an initial peak near 600 km/s to approximately 500 km/s by the end of the reporting period. The solar wind environment is expected to remain enhanced through February 20 due to
continued but weakening CH HSS influences.


Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, February 19, 2026, by F. K. Janda, OK1HH:


"Overall solar activity was relatively high in the first week of February,
with the number of sunspot groups on the solar disk ranging from seven to
nine. Over the next ten days, we observed an almost uninterrupted decline, at the end of which there were only three sunspot groups remaining on the disk.


"Significant eruptions could only occur in one of them: AR 4374. Before it
set behind the western limb of the solar disk, one of the few more powerful eruptions was observed in it. It happened on February 16, with the peak at
0436 UT, accompanied by a CME, partially heading towards Earth. The arrival
was expected on February 19. Although it did so at 1501 UT, Earth only encountered the edge of the particle cloud - and in fact, almost nothing happened.


"Geomagnetic activity was elevated on February 15-16. The phenomenon began
with a positive phase of disturbance in the evening hours, during which there was a noticeable improvement in shortwave propagation conditions. A
significant deterioration naturally followed on February 16, partially also
on February 17.


"Any geomagnetic disturbance at the beginning of the predicted period should
be short (on 19th), while another disturbance can be expected around February 24. Given that solar activity will be on the rise again at that time, a positive phase of the disturbance can be expected."


Geomagnetic field activity is expected to be at unsettled to active levels on February 24 and 25, and on March 5 to 7 due to recurrent negative polarity CH HSS effects. Active conditions are likely on March 12 following a solar
sector boundary crossing, then again on March 14 with the onset of a positive polarity CH HSS. Barring the potential for CME activity, mostly quiet to unsettled levels are expected until February 23, and then February 26 to
March 4.


The Predicted Planetary A Index for February 21 to 27 is 5, 5, 8, 20, 20, 8, and 5, with a mean of 10.1. The Predicted Planetary K Index is 2, 2, 3, 5, 5, 3, and 2, with a mean of 3.1. 10.7-centimeter flux is 105, 120, 130, 135,
130, 130, and 140, with a mean of 127.1.


For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation [ http://www.arrl.org/propagation?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL
] and the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals [ http://arrl.org/propagation-of-rf-signals ] . For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere [ http://arrl.org/the-sun-the-earth-the-ionosphere ] . Information and
tutorials on propagation can be found at, http://k9la.us/ [ http://k9la.us/ ]
.


Also, check this: "Understanding Solar Indices" from September 2002 QST https://bit.ly/3Rc8Njt [ https://bit.ly/3Rc8Njt ] .

NNNN
/EX

ARRL The National Association for Amateur Radio(R)


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